Question

组，我正在尝试使用一个变量@Customer创建一个存储过程。我想要做的是在WHERE子句中添加一些内容，说明它是否为数字搜索CustomerID字段，其中输入的数字为LIKE CustomerID ...如果输入了char，则搜索CustomerName字段，其中输入的文本为LIKE CustomerName。以下是我想要做的一个例子：

CREATE PROCEDURE [dbo].[uspGetCustomer] (@Customer VARCHAR(100))

AS

SET NOCOUNT ON

SELECT * 
FROM dbo.Customers
WHERE CASE WHEN ISNUMERIC(@Customer) THEN CustomerID LIKE @Customer + '%'
ELSE CustomerName LIKE @Customer + '%' END

有什么建议吗？

Answer 1

我会使用IF语句来实现，因为将该逻辑放在WHERE中会使以后难以阅读：

DECLARE @match = @CustomerID + '%'

IF ISNUMERIC(@CustomerID) = 1 
BEGIN
     SELECT * FROM CUSTOMERS WHERE CustomerID LIKE @match
END ELSE BEGIN
     SELECT * FROM CUSTOMERS WHERE CustomerNAME LIKE @match
END

更新：我想知道CustomerID字段是否是INT。如果是这样，那么我会像这样更改查询（并删除@match变量）：

    ... WHERE CustomerID = Cast(@CustomerID as INT) --if numeric
    ... WHERE CustomerNAME = @CustomerID + '%'      --if not numeric

但是，如果它是一个奇怪的VARCHAR字段以数字开头并以其他数据结尾，如'11_blah'，则LIKE加通配符正常工作

Answer 2

尝试解决这两个条件的单个SQL语句将导致最差的执行计划。记住SQL必须生成一个单独的计划来满足@variable的任何值。在你的情况下@customerID是数字时，正确的计划是使用CustomerID上的索引。但是当@customerID是一个名称时，正确的访问权限将是CustomerName的索引。鉴于这种困境，优化器可能会选择执行全扫描的计划，即。两种情况都没有优化。

正确的做法是确定应用中的，如果是ID或名称，并调用两个单独的存储过程，uspGetCustomerByID和uspGetCustomerByName，根据输入的值。如果你必须通过一个'魔术'API入口点（全能的uspGetCustomer）来做到这一点，那么你已经得到了很好的答案。

Answer 3

它可能只是我，但使用单个变量来表示两个不同的字段给了我糟糕的练习意志。我会重写这个存储过程以接受两个不同的可空变量（一个int，CustomerID和一个varchar，CustomerName）。它看起来像这样：

CREATE PROCEDURE [dbo].[uspGetCustomer] (
@CustomerID int = null, 
@CustomerName VARCHAR(100) = null)

AS

IF @CustomerID IS NOT NULL BEGIN
     SELECT * FROM Customers WHERE CustomerID = @CustomerID
END ELSE IF @CustomerName IS NOT NULL BEGIN
     SELECT * FROM Customers WHERE CustomerName LIKE @CustomerName
END ELSE
     --error handling, return empty set maybe?
END

如果这不是一个选项，那么你仍然可以使用：

CREATE PROCEDURE [dbo].[uspGetCustomer] (@Customer VARCHAR(100))

AS

DECLARE @NameMatch;

IF ISNUMERIC(@Customer) = 1 BEGIN
     SELECT * FROM Customers WHERE CustomerID = CAST (@Customer AS int)
END ELSE BEGIN
     SET @NameMatch = '%' + @Customer + '%'
     SELECT * FROM Customers WHERE CustomerName LIKE @NameMatch
END

Answer 4

使用：

CREATE PROCEDURE [dbo].[uspGetCustomer] (@Customer VARCHAR(100))
AS

BEGIN

IF ISNUMERIC(@Customer) = 1
  BEGIN
    SELECT *
      FROM dbo.CUSTOMERS
     WHERE customerid LIKE @Customer + '%'
  END
ELSE
  BEGIN
    SELECT *
      FROM dbo.CUSTOMERS
     WHERE customername LIKE @Customer + '%'
  END

END

Answer 5

做这样的事情：

CREATE PROCEDURE [dbo].[uspGetCustomer] (
    @CustomerID INT = NULL
    @Customer VARCHAR(100) = NULL
)

AS

SET NOCOUNT ON

IF @CustomerID is not null
BEGIN
    SELECT * FROM dbo.Customers
    WHERE CustomerID = @CustomerID
END
ELSE
BEGIN
    SELECT * FROM dbo.Customers
    WHERE CustomerName LIKE @CustomerID + '%'
END

SET NOCOUNT OFF

Answer 6

我会保持简单，并假设客户名称永远不会是数字：

SELECT * 
FROM dbo.Customers
WHERE CustomerID LIKE @Customer + '%'
OR CustomerName LIKE @Customer + '%'

或者，如果您确实不希望将数字客户与其名称匹配，则可以检查如下：

WHERE (IsNumeric(@Customer) = 1 AND CustomerID LIKE @Customer + '%')
OR (IsNumeric(@Customer) = 0 AND CustomerName LIKE @Customer + '%')

但是，您如何搜索具有数字名称的客户？顺便说一下......如果你搜索121，这样的搜索会找到客户12。

Answer 7

SELECT  * 
FROM    dbo.Customers
WHERE   ISNUMERIC(@Customer) = 1
        AND CustomerID = CAST(@Customer AS INTEGER)
UNION ALL
SELECT  *
FROM    dbo.Customers
WHERE   NOT ISNUMERIC(@Customer) = 1
        AND CustomerName LIKE @Customer + '%'

这将使用CustomerID和CustomerName

上的相应索引

Answer 8

我相信这样做会：

WHERE CustomerID LIKE
  CASE WHEN IsNumeric(@Customer) = 1 THEN 
    CustomerID 
  ELSE
    CustomerName + '%'
  END

Answer 9

哦，就这样做吧....

IF ISNUMERIC(@Customer) THEN
SELECT * FROM .... CustomerID = @Customer

ELSE 
SELECT * FROM ... CustomerName LIKE @Customer

但是你想让它更易于维护...

declare @basequery NVARCHAR(4000)
declare @params NVARCHAR(4000)

set @base_query = 'select * from dbo.Customers where '

IF ISNUMERIC(@Customer) THEN
  SET @base_query = @base_query + 'customerid = @xCustomer'
  SET @params = '@xCustomer int'
END
ELSE
  SET @base_query = @base_query + 'customerName LIKE @xCustomer + ''%'' '
  SET @params = '@xCustomer nvarchar(1000)'
END

exec sp_execuresql @base_query, @params, @Customer

当然我只会推荐这种动态的sql来进行更复杂的过滤。

Answer 10

保持简单，每个都有一个索引，在前端确定它是哪一个并设置正确的参数。

CREATE PROCEDURE dbo.getCustomer 
(@CustomerID int = null, 
@CustomerName VARCHAR(100) = null)
AS
SET NOCOUNT ON

SELECT * 
FROM Customers 
WHERE CustomerID = @CustomerID
or CustomerName like @CustomerName + '%'

存储过程WHERE LIKE ID或NAME

10 个答案: